Blueprint Reading & Interpretation Flashcards

On a dryer wiring diagram, terminals labeled L1 and L2 represent:

Answer: The two 120V legs of a 240V supply

L1 and L2 are the two hot legs of a 240V split-phase supply, each carrying 120V to neutral.

In a blueprint title block, the 'revision history' section is important during recycling assessment because it:

Answer: Records design changes that may affect component compatibility

The revision history documents changes to the design, which is critical when sourcing replacement parts or assessing material composition.

A schematic shows a component symbol with two parallel horizontal lines of unequal length. This represents a:

Answer: Battery or DC power source

Two parallel lines of unequal length is the standard schematic symbol for a battery or DC power source, with the longer line being the positive terminal.

When interpreting a heat pump blueprint, the reversing valve is identified because it:

Answer: Has four refrigerant line connections shown on the diagram

A reversing (four-way) valve has four refrigerant ports — suction, discharge, and two to the indoor/outdoor coils — which distinguishes it on diagrams.

A CAR technician reads a blueprint scale of 1:10. If a component measures 3 cm on the drawing, what is its actual size?

Answer: 30 cm

At a 1:10 scale, the actual object is 10 times larger than the drawing, so 3 cm × 10 = 30 cm.

On an appliance schematic, a component labeled 'OLP' is typically found protecting which part?

Answer: The compressor motor

OLP stands for Overload Protector and is mounted on or near the compressor to cut power if the motor overheats or draws excessive current.

Which blueprint view shows the appliance as if cut horizontally to reveal interior shelf and compartment layout?

Answer: Horizontal section (plan) view

A horizontal section or plan view cuts the appliance at a horizontal plane to show compartment arrangement from above.